From their shopfront theatre in Mandalay, the Moustache Brothers tell bad jokes in barely comprehensible English about Burma's backward-looking generals and every few years they get flung into jail for it.

There are three in the troupe - actually two brothers and their cousin - and each evening they wait for the tourists to turn up and justify their performance of slapstick, dance and strangled humour about the army looking after itself while the rest of Burma goes to the dogs.

It's not the money they need the tourists for, although that undoubtedly helps in a country where most people spend most of their cash just on feeding their families. But in the peculiar world inhabited by Burma's military leadership, jokes against the government are just about acceptable provided they are told to foreigners.

The Moustache Brothers have been part of the tourist trail since two of its members, Par Par Lay and Lu Zaw, were released from seven years in labour camps for bringing humour to what everyone in Burma knows: the system is so riddled with corruption you cannot tell the difference between a thief and a government worker.

The Moustache Brothers have reached an uneasy truce with the regime (Lay was detained for a month after the pro-democracy demonstrations in September) that permits them to perform, provided it's in English, only in their own theatre and for tourists.

This has left the troupe in agreement with the junta on one thing at least: that a tourist boycott of Burma is a mistake. The military wants foreigners to keep coming because they provide a kind of legitimacy as well as hard currency. That is a good reason not to go. But ordinary Burmese say tourism provides many with the means to feed their families.

Some money will fall into the state's hands but, as a reporter pretending to be a tourist - the only way a journalist can get into Burma - it was easy enough to direct where most of the cash goes by avoiding corporate hotels, eating in smaller restaurants and buying from family-owned shops. It's also a good way to hear from ordinary people what is going on.

Tourists are witnesses to the state of the monasteries after the regime purged them of monks to break the pro-democracy protests. The monks who remain are often willing to talk discreetly about the assaults on them and their supporters and about how the military is keeping up the pressure despite the generals' attempts to persuade the outside world that everything is back to Burma's abnormal form of normality.

The key, though, is to stay away from organised tours that funnel visitors into hotels and on to trips run by the regime's lackeys. Of all the ordinary Burmese I asked if they agreed with a tourist boycott, only one said yes, on the grounds it would deepen the misery and force people to revolt. But then he also thought that the Americans were on the verge of invading to overthrow the regime.

It's not clear-cut, though. The sports and cultural boycott of apartheid South Africa stung many whites because it said that, however much they saw themselves as an outpost of European civilisation, most of Europe did not agree with them.

But popular boycotts of countries such as Burma or Zimbabwe have less impact than hitting a regime where it really hurts. Zimbabwe's ruling elite can no longer go shopping in Europe and they have been forced to pull their children out of British boarding schools and American universities. Their companies are blacklisted. That hurts.

Burma's business elite, which is closely aligned to the regime, is also complaining, not least a construction and airline magnate called Tay Zar. His businesses have run into serious problems because of the popular boycott at home and sanctions by the West. He is pleading with foreign governments to lift the boycott and is making it known to the generals.

The UK can afford to take the moral high ground on Burma because it has no weapons deals at stake or oil interests to protect. Which is why we do not hear much from France on the subject: Burma is the home of the Total oil company, which hands over hundreds of millions of dollars a year to the regime in revenues.

The Moustache Brothers can give you chapter and verse on this. If you want to help Burma, they say, come and visit. Just don't fill your car up with Total petrol on the way from the airport.